Chipgeek, I agree. Quad core with turbo mode is like having the best of both words. Great multithreaded performance through multiple cores, and great single threaded performance through higher frequencies.
Just look at the problem with Phenom. AMD is going from a 3.2GHz K8 dual core architecture to a 2.3GHz K8L quad core architecture, and in single threaded apps, it's a big step backwards.
Kentsfield and Yorkfield don't have as much of a problem, primarily because Intel has positioned high end quad core frequencies somewhat close to their top dual core frequencies. Of course, this is mostly artificial, since it ought to be possible to manufacture 3.x GHz dual cores, if quads are also hitting 3.0GHz. But as you mention, doing this creates a positioning issue and forces the consumer to chose between multithreaded performance or single threaded performance.
But with Nehalem, consumers won't have this problem. It's probably one of the leading features of the micro-architecture, and if it works well, Intel should put the spotlight directly on it.